How to use this image

All examples in this guide use the public image. If you've mirrored the repository for your own use (for example, to your Docker Hub namespace), update your commands to reference the mirrored image instead of the public one.

For example:

• Public image: dhi.io/<repository>:<tag>
• Mirrored image: <your-namespace>/dhi-<repository>:<tag>

For the examples, you must first use docker login dhi.io to authenticate to the registry to pull the images.

What's included in this Headlamp Hardened Image

This Docker Hardened Headlamp image includes the Kubernetes web UI backend and the compiled React frontend it serves. The headlamp-server binary listens on port 4466 and both serves the SPA and proxies requests to the Kubernetes API using an in-cluster ServiceAccount or a mounted kubeconfig.

The image bundles:

• headlamp-server (Go backend) at /usr/bin/headlamp-server
• The compiled frontend at /usr/share/headlamp/frontend
• User plugin directory at /headlamp/plugins and bundled static plugins at /headlamp/static-plugins
• A /headlamp/headlamp-server symlink pointing to the binary for parity with the upstream image layout

Start a Headlamp image

Run the container against an existing cluster by mounting a kubeconfig into the nonroot user's home directory:

docker run --rm -p 4466:4466 \
  -v ~/.kube/config:/home/nonroot/.kube/config:ro \
  dhi.io/headlamp:<tag>

Or pass the kubeconfig explicitly with the -kubeconfig flag:

docker run --rm -p 4466:4466 \
  -v ~/.kube/config:/kubeconfig:ro \
  dhi.io/headlamp:<tag> \
  -kubeconfig /kubeconfig

Open http://localhost:4466 in your browser to access the Headlamp UI.

Common headlamp use cases

Deploy Headlamp in-cluster

When Headlamp runs inside the cluster it uses its ServiceAccount token instead of a kubeconfig. Replace <your-registry-secret> with your Kubernetes image pull secret⁠ and <tag> with the desired image tag.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: headlamp
  namespace: kube-system
spec:
  replicas: 1
  selector:
    matchLabels:
      app: headlamp
  template:
    metadata:
      labels:
        app: headlamp
    spec:
      serviceAccountName: headlamp-admin
      imagePullSecrets:
        - name: <your-registry-secret>
      containers:
        - name: headlamp
          image: dhi.io/headlamp:<tag>
          ports:
            - containerPort: 4466
          securityContext:
            runAsNonRoot: true
            runAsUser: 65532
            runAsGroup: 65532
            allowPrivilegeEscalation: false

A ServiceAccount with cluster-scoped read permissions (and any write permissions your operators need) must be created separately. See the upstream Headlamp installation docs for the full role bindings.

Non-hardened images vs. Docker Hardened Images

Key differences

Why no shell or package manager?

Docker Hardened Images prioritize security through minimalism:

• Reduced attack surface: Fewer binaries mean fewer potential vulnerabilities
• Immutable infrastructure: Runtime containers shouldn't be modified after deployment
• Compliance ready: Meets strict security requirements for regulated environments

The hardened images intended for runtime don't contain a shell nor any tools for debugging. Common debugging methods for applications built with Docker Hardened Images include:

• Docker Debug⁠ to attach to containers
• Docker's Image Mount feature to mount debugging tools
• Ecosystem-specific debugging approaches

Docker Debug provides a shell, common debugging tools, and lets you install other tools in an ephemeral, writable layer that only exists during the debugging session.

For example, you can use Docker Debug:

docker debug <image-name>

or mount debugging tools with the Image Mount feature:

docker run --rm -it --pid container:my-container \
  --mount=type=image,source=dhi.io/busybox,destination=/dbg,ro \
  dhi.io/headlamp:<tag> /dbg/bin/sh

Image variants

Docker Hardened Images come in different variants depending on their intended use.

Runtime variants are designed to run your application in production. These images are intended to be used either directly or as the FROM image in the final stage of a multi-stage build. These images typically:

• Run as the nonroot user
• Do not include a shell or a package manager
• Contain only the minimal set of libraries needed to run the app

Build-time variants typically include dev in the variant name and are intended for use in the first stage of a multi-stage Dockerfile. These images typically:

• Run as the root user
• Include a shell and package manager
• Are used to build or compile applications

FIPS variants include fips in the variant name and tag. They come in both runtime and build-time variants. These variants use cryptographic modules that have been validated under FIPS 140, a U.S. government standard for secure cryptographic operations. The Headlamp FIPS build embeds Go's NIST-validated crypto module via GOFIPS140=v1.0.0, so the binary starts in FIPS-aware mode by default. If your cluster's TLS handshake surfaces post-quantum ML-KEM issues, set GODEBUG=tlsmlkem=0 on the Deployment.

To view the image variants and get more information about them, select the Tags tab for this repository, and then select a tag.

Migrate to a Docker Hardened Image

Switching to the hardened Headlamp image does not require any special changes. You can use it as a drop-in replacement for the standard Headlamp (ghcr.io/headlamp-k8s/headlamp) image in your existing workflows and configurations. The default entrypoint and exposed port match upstream; the server, plugin directory (/headlamp/plugins), and static plugins (/headlamp/static-plugins) work out of the box. The bundled frontend is served from /usr/share/headlamp/frontend (the image's default -html-static-dir); override that flag only if you relocate it.

Migration steps

1. Replace the image reference in your Docker run command, Compose file, or Kubernetes manifest.

2. All your existing command-line arguments, environment variables, port mappings, and network settings remain the same.

3. Test your migration and use the troubleshooting tips below if you encounter any issues.

Troubleshooting migration

General debugging

The hardened images intended for runtime don't contain a shell nor any tools for debugging. The recommended method for debugging applications built with Docker Hardened Images is to use Docker Debug⁠ to attach to these containers. Docker Debug provides a shell, common debugging tools, and lets you install other tools in an ephemeral, writable layer that only exists during the debugging session.

Permissions

By default image variants intended for runtime, run as the nonroot user. Ensure that necessary files and directories are accessible to the nonroot user. You may need to copy files to different directories or change permissions so your application running as the nonroot user can access them.

Privileged ports

Non-dev hardened images run as a nonroot user by default. As a result, applications in these images can't bind to privileged ports (below 1024) when running in Kubernetes or in Docker Engine versions older than 20.10.

No shell

By default, image variants intended for runtime don't contain a shell. Use dev images in build stages to run shell commands and then copy any necessary artifacts into the runtime stage. In addition, use Docker Debug to debug containers with no shell.

Entry point

Docker Hardened Images may have different entry points than images such as Docker Official Images. Use docker inspect to inspect entry points for Docker Hardened Images and update your Dockerfile if necessary.